This invention relates to an apparatus for imparting independent rotational and axial movement to a workpiece.
More specifically, the invention provides for independent rotational incremental movement and translational incremental movement to tubular members or the like, particularly when work is to be done on the tubular member, or another member such as a fin structure is to be applied to the tubular member. The tubular member does not have to be round in cross-section and may be either hollow or solid.
By providing for independent translational and rotational movement of the workpiece, a more accurate control of the incremental and total movement of the workpiece is obtained. Moreover, for the sake of accuracy and precise movement, it is important that the translation movement imparted to the workpiece is not affected by and does not affect the rotational movement of the workpiece, and vice-versa.
Apparatus and mechanisms for imparting both rotational and translational movement to a workpiece are known. However, such apparatus do not provide for separate and independent incremental rotational and translational movement without one type of movement affecting the other. Specifically, with the heretofore known apparatus, rotational and incremental movement can be imparted to a workpiece, but one type of movement affects the other. Hence, the net translational or rotational movement of the workpiece is dependent upon the amount of separate translational and separate rotational movement imparted to the workpiece.
In the heretofore known apparatus which includes both means for imparting translational movement and means for imparting rotational movement, the net translational movement will vary in accordance with the amount of rotational movement imparted to the workpiece. Therefore, if a predetermined amount of translational movement is imparted, the workpiece will advance translationally different amounts in accordance with the amount of and direction of rotational movement imparted to the workpiece. In a similar manner, when rotational movement is imparted to the workpiece, the amount of angular rotation imparted to the workpiece is dependent not only on the rotational movement, but on the amount and direction of the translational movement imparted.
One example of an apparatus for moving a workpiece both translationally and rotationally is set forth in Connor et al, U.S. Pat. No. 2,429,201. Connor et al provides for two gears, a casing gear and a sun gear which are interrelated. By rotating the casing gear and the sun gear at the same speed and in the same direction, the workpiece-bar will be rotated, but the bar will not be moved translationally. In order to obtain translational movement of the bar, it is necessary to rotate the casing gear and the sun gear at different speeds. The relationship between the rotational movement and the translational is determined and varied by adjusting the relative speeds of rotation imparted to the casing gear and the sun gear. Therefore, the rate and direction of feed as well as direction of rotation of the tube are all interrelated and dependent upon the relative speeds and direction of rotation of the casing and the sun gear.
Another example of an apparatus for moving a workpiece both rotationally and translationally is set forth in Wolszek, U.S. Pat. No. 3,517,844. Wolszek shows the use of two drive belts to control the rotation and translational advancement of a workpiece. One belt drives a housing and another belt drives a sleeve. The housing and the sleeve are geared to work together as a unit in order to rotate and move a workpiece translationally. Movement of the workpiece whether rotational, translational or both is dependent on the speed of rotation of the housing and the sleeve. When the speed of rotation of the housing and the sleeve are the same, the workpiece rotates with no translational movement. When the housing is rotated and the sleeve is stopped, the workpiece is moved transltionally and rotated. Hence, rotational and translational movement of the workpiece is dependent on two movements which are not independent of each other.